LIMA, PERU
— With mounting evidence of electoral fraud, massive street manifestations and increasing international pressure as a backdrop, the Peruvian government announced Wednesday night that controversial presidential elections will go to a runoff.

President Alberto Fujimori had been advancing in slow-moving official tallies toward the simple majority he needed from Sunday's first-round vote to win an unprecedented third term. But after three days that left the nation on tenterhooks and the world warning of grave consequences over a stolen election, Peru's National Electoral Process Office (ONPE) said President Fujimori would fall just short of the votes needed, forcing him into a runoff with economist Alejandro Toledo.

As Peru girds now for a runoff in late May or early June, the perception is widespread that without intense pressure from abroad, Fujimori would today be basking in a first-round victory. "Without the internal and international pressure, the government would have declared Fujimori the outright winner," says Lima political analyst Fernando Rospigliosi.

After exit polls from Peruvian watchdog groups and polling firms concluded as early as Sunday evening that a runoff would be necessary, Fujimori's gradual advance in the official count toward the 50-percent-plus-one mark caused blunt international reaction - especially from the United States.

"The moment I saw the American ambassador on TV saying emphatically that there should be a second round, I knew there would be one," Mr. Rospigliosi says. "The message is that the international community is watching, and that it is not going to permit the imposition of autocratic governments even if they have a democratic facade."

Fujimori will likely spin that criticism to his advantage in the weeks leading to the runoff. He frequently calls himself a different kind of democrat, misunderstood by the international community.

Signalling the hyper-nationalist campaign to come, Fujimori vice-presidential candidate and former foreign minister Francisco Tudela lambasted the US pressure for a runoff, which had come from as high as the White House and Congress.

Mr. Tudela condemned "in the most energetic terms the fact that a foreign government would emit a judgment value about elections in another country before the official count is in." During the campaign, Tudela condemned the calls of international observer groups for stronger guarantees of transparent elections as "neocolonialism."

Announcement of a runoff vote has cut the tension in a nation many thought was on the brink of a social explosion over growing signs of electoral fraud. The thousands of largely student protesters that had been in a nearly permanent vigil in the streets of Lima since Tuesday afternoon erupted in sheer euphoria at the news, cheering Mr. Toledo as he spoke to them from the balcony of a hotel in central Lima.

"I am not a Toledo sympathizer, but we are tired of 10 years with Fujimori, and we don't want him to stay in power based on fraud," said Luis Monroe, who was among the many celebrating the news in the Plaza de San Martin Wednesday night.

Ever since voting ended Sunday afternoon, there have been increasing reports of irregularities in the tallying process - casting dark clouds of doubt over the ONPE's competence and impartiality.

There have been a "collection of imbalances and silences in [handling] the process since voting that have done nothing else but confirm the feeling that something very sinister is happening," says Eduardo Stein, the leader of the Organization of American States' election-observer mission. Mr. Stein qualified the vote-counting process as "highly irregular."

According to the local election-observer-group Transparencia, there were unexplained delays in the delivery of the ballot tally sheets to the centers where the results are entered into computers. In one Lima district a truck full of tally sheets was discovered on the streets on Tuesday.

Some of the reported irregularities verged on the bizarre. On Sunday, Transparencia confirmed the existence of a Web page in Australia from which votes could apparently be entered into ONPE's computer system. The next day local reporters spotted four men at a Lima Internet cafe entering information from what appeared to be original voting tally sheets onto a Web page. When confronted, the men left the Internet cafe and retreated to a local office of Fujimori's campaign organization.

Opponent gains some ground

Toledo appears to be entering this second campaign period in an advantageous position. Five other opposition candidates have closed ranks behind him, vowing their support to him in a second round. This support could translate into advantages other than votes on election day, if it is consolidated into a unified voting bloc - or at least the promise of it - in Congress.

"If he achieves an alliance, Toledo would have a majority in Congress. He could say, 'Vote for me because I can guarantee governability,' " says political analyst Fernando Tuesta. At this point, Fujimori's party has a simple majority in Congress.

But Toledo will also have some serious obstacles. With official results showing Fujimori took something over 49.8 percent of the vote to Toledo's 40.3 percent, the path is open for Fujimori to claim an increase of a few tenths of a percent in the runoff.

Fujimori's government was highly criticized by international observer groups in the months before elections for having manipulated the pre-electoral process to tilt the playing field in his favor. The government-influenced television stations are accused of giving opposition candidates minimal coverage throughout the campaign.

"There will be a strong battle to improve conditions in the second round. The government is not going to give in easily; it will try to do what it did in the first round," predicts Rospigliosi.